EUV/Soft X-Ray Interference Lithography

Based on the coherent radiation from an undulator source, extreme UV interference lithography (EUV-IL) technology is considered as the leading candidate for future nodes of high-volume semiconductor manufacturing. The throughput of this technique is much higher than that of traditional lithography methods such as e-beam lithography (EBL) and laser interference lithography (LIL). Different types of interference schemes based on reflection mirrors and transmission diffraction masks have been described in this chapter. Achromatic Talbot lithography (ATL) and the soft X-ray interference lithography (SXIL) with different photon energies have also been developed to produce highly dense, high-resolution periodic nanostructures. Two scan-exposure techniques, one is the method employing the broadband Talbot effect and the other based on the multi-grating EUV-IL with an order sorting aperture (OSA), have been used to obtain periodic nanostructures over large areas. Applications of EUV-IL on EUV-resist testing and nano-science have been illustrated

Low genetic diversity of Phytophthora infestans population in potato in north China

Late blight, caused by Phytophthora infestans is the most important disease of potato (Solanum tuberosum). This study reveals the genetic diversity of P. infestans population in north China. A total of 134 strains of P. infestans were isolated from different agricultural fields in Hebei, Liaoning, Jinlin and Heilongjiang Provinces in north China. The genetic variation among these strains were analyzed using 15 ‘simple-sequence repeat’ (SSR) markers. The results show that forty different SSR genotypes and an average of 3.8 (range 2 to 9) alleles per locus were found. Low genetic diversity (Shannon’s diversity index = 0.26) was found among these 134 strains from four provinces, revealing the presence of clonal populations of the pathogen in this region. The average heterozygosity was 0.162, indicating the low level of genetic variations of P. infestans populations. There was no correlation between population genetic diversity of P. infestans and geographical origin. These results provided a foundation for making integrated control measures in the future.Key words: Phytophthora infestans, population genetics, simple-sequence repeat (SSR), potato late blight